想创建一个JMenuBar。如果window-JFrame.width 小到显示JMenuBar 的所有JMenu,JMenuBar 中会出现一个Button,所有隐藏的JMenu 都可以在下拉列表中选择。请问我怎样才能意识到呢?
问问题
1279 次
3 回答
1
用于CardLayout
拥有一个包含普通菜单和使用按钮实现的菜单的面板。然后添加一个ComponentListener
( ) 并在侦听器的方法ComponentAdapter
中选择所需的菜单实现。componentResized()
在代码中,它大致如下所示:
JMenuBar createCustomMenu() {
final CardLayout layout = new CardLayout();
final JMenuBar menu = new JMenuBar();
menu.setLayout(layout);
// Here you should create the normal, wide menu
JComponent normalMenu = createNormalMenu();
// Here you create the compressed, one button version
JComponent compressedMenu = createCompressedMenu();
menu.add(normalMenu, "normal");
menu.add(compressedMenu, "compressed");
menu.addComponentListener(new ComponentAdapter() {
public void componentResized(ComponentEvent e) {
if (menu.getPreferredSize().getWidth() > menu.getWidth()) {
layout.show(menu, "compressed");
} else {
layout.show(menu, "normal");
}
}
});
return menu;
}
(编辑:更改为 return JMenuBar
,因为它似乎工作得很好)
于 2013-07-23T09:39:31.587 回答
1
这是我 5 年前玩过的一些旧代码。它已经很长时间了,我什至不记得代码的效果如何。它是为 JToolBar 设计的,但它可能会为您提供一些关于如何使用 JMenuBar 执行此操作的想法:
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
/**
*
* @author subanark
*/
public class PopupMenuLayout implements java.awt.LayoutManager
{
private JPopupMenu popupMenu = new JPopupMenu();
private JButton popupButton = new JButton(new PopupAction());
/** Creates a new instance of PopupMenuLayout */
public PopupMenuLayout()
{
}
/** If the layout manager uses a per-component string,
* adds the component <code>comp</code> to the layout,
* associating it
* with the string specified by <code>name</code>.
*
* @param name the string to be associated with the component
* @param comp the component to be added
*/
public void addLayoutComponent(String name, Component comp)
{
}
/**
* Lays out the specified container.
* @param parent the container to be laid out
*/
public void layoutContainer(Container parent)
{
// Position all buttons in the container
Insets insets = parent.getInsets();
int x = insets.left;
int y = insets.top;
System.out.println("bottom: " + insets.bottom);
int spaceUsed = insets.right + insets.left;
for (int i = 0; i < parent.getComponentCount(); i++ )
{
Component aComponent = parent.getComponent(i);
aComponent.setSize(aComponent.getPreferredSize());
aComponent.setLocation(x,y);
int componentWidth = aComponent.getPreferredSize().width;
x += componentWidth;
spaceUsed += componentWidth;
}
// All the buttons won't fit, add extender button
// Note: the size of the extender button changes once it is added
// to the container. Add it here so correct width is used.
int parentWidth = parent.getSize().width;
if (spaceUsed > parentWidth)
{
popupMenu.removeAll();
parent.add(popupButton);
popupButton.setSize( popupButton.getPreferredSize() );
int popupX = parentWidth - insets.right - popupButton.getSize().width;
popupButton.setLocation(popupX, y );
spaceUsed += popupButton.getSize().width;
}
// Remove buttons that don't fit and add to the popup menu
// System.out.println(spaceUsed + " ::: " + parentWidth);
int lastVisibleButtonIndex = 1;
while (spaceUsed > parentWidth)
{
lastVisibleButtonIndex++;
int last = parent.getComponentCount() - lastVisibleButtonIndex;
Component component = parent.getComponent( last );
component.setVisible( false );
spaceUsed -= component.getSize().width;
addComponentToPopup(component);
// popupButton.setLocation( button.getLocation() );
// System.out.println(spaceUsed + " : " + parentWidth);
}
}
private void addComponentToPopup(Component component)
{
System.out.println(component.getClass());
if (component instanceof JButton)
{
JButton button = (JButton)component;
JMenuItem menuItem = new JMenuItem(button.getText());
menuItem.setIcon( button.getIcon() );
ActionListener[] listeners = button.getActionListeners();
for (int i = 0; i < listeners.length; i++)
menuItem.addActionListener( listeners[i] );
popupMenu.insert(menuItem, 0);
}
if (component instanceof JToolBar.Separator)
{
popupMenu.insert( new JSeparator(), 0);
}
}
/**
* Calculates the minimum size dimensions for the specified
* container, given the components it contains.
* @param parent the component to be laid out
* @see #preferredLayoutSize
*/
public Dimension minimumLayoutSize(Container parent)
{
return popupButton.getMinimumSize();
}
/** Calculates the preferred size dimensions for the specified
* container, given the components it contains.
* @param parent the container to be laid out
*
* @see #minimumLayoutSize
*/
public Dimension preferredLayoutSize(Container parent)
{
// Move all components to the container and remove the extender button
parent.remove(popupButton);
/*
while ( popupMenu.getComponentCount() > 0 )
{
Component aComponent = popupMenu.getComponent(0);
popupMenu.remove(aComponent);
parent.add(aComponent);
}
*/
// Calculate the width of all components in the container
Dimension d = new Dimension();
d.width += parent.getInsets().right + parent.getInsets().left;
for (int i = 0; i < parent.getComponents().length; i++)
{
Component component = parent.getComponent(i);
component.setVisible( true );
d.width += component.getPreferredSize().width;
d.height = Math.max(d.height, component.getPreferredSize().height);
}
// d.height += parent.getInsets().top + parent.getInsets().bottom + 5;
d.height += parent.getInsets().top + parent.getInsets().bottom;
return d;
}
/** Removes the specified component from the layout.
* @param comp the component to be removed
*/
public void removeLayoutComponent(Component comp)
{
}
protected class PopupAction extends AbstractAction
{
public PopupAction()
{
super(">>");
}
public void actionPerformed(ActionEvent e)
{
JComponent component = (JComponent)e.getSource();
popupMenu.show(component,0,component.getHeight());
}
}
public static void main(String[] argv)
{
ActionListener simpleAction = new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
System.out.println(e.getActionCommand());
}
};
JToolBar toolBar = new JToolBar();
toolBar.setLayout(new PopupMenuLayout());
toolBar.add( createButton("one", simpleAction) );
toolBar.add( createButton("two", simpleAction) );
toolBar.add( createButton("three", simpleAction) );
toolBar.add( createButton("four", simpleAction) );
toolBar.add( createButton("five", simpleAction) );
toolBar.add( createButton("six", simpleAction) );
toolBar.addSeparator();
toolBar.add( createButton("seven", simpleAction) );
toolBar.add( createButton("eight", simpleAction) );
toolBar.addSeparator();
toolBar.add( createButton("nine", simpleAction) );
toolBar.add( createButton("ten", simpleAction) );
JFrame f = new JFrame();
f.getContentPane().setLayout(new BorderLayout());
f.getContentPane().add(toolBar,BorderLayout.NORTH);
f.setBounds(300,200,400,300);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
private static JButton createButton(String text, ActionListener listener)
{
JButton button = new JButton(text);
button.addActionListener( listener );
return button;
}
}
在这种情况下,工具栏按钮在没有可用空间时转换为 JMenu。在您的情况下,您已经有一个 JMenu,因此您应该能够将 JMenu 从 JMenuBar 移动到弹出菜单。但是,在确定菜单栏的首选大小之前,您需要更改代码以始终将菜单从弹出菜单移回菜单栏。
于 2013-07-23T15:04:25.257 回答